I have found these tablets are very good as a preventative and reactive response for muscle cramps. The tablets dissolve in the mouth and provide relief very quickly. They are more convenient to use than most forms of magnesium tablets. In recent years I have had a tendency to get hand cramps while driving and hamstring cramps at night. Tablets taken when the cramps occur seem to solve the problem or if I have had a long hot day on the bowling greens a recommended dose before retiring prevents being rudely awoken during the night with a hamstring seizure. I'm a committed user.